The present invention is directed to a shutoff valve for pipelines or containers and includes a housing with a flap shaped cutoff part pivotably supported within the passageway formed by the housing. The cutoff part can be pivoted between a closed position in sealed contact with a valve seat in the housing to an open position by means of an actuator including a shifter rod aligned with the pivot axis of the cutoff member. A support shaft is attached to the cutoff part on one side and projects beyond the circumference of the cutoff part and has a ball member at its outer end supported in a universally pivotable manner within the housing wall. On the diametrically opposite side of the cutoff part from the shaft the cutoff part is secured to the axial displaceable shifter rod by the combination of a guide pin and a sliding guide. The sliding guide is arranged to extend obliquely to the axis of the shifter rod. The relative movement of the guide pin and the sliding guide effects the pivotable movement of the cutoff part so that it can be moved between the closed and opened positions relative to the flow passageway in the housing.
Shutoff valves of this type are known, such as disclosed in the German patent publication No. 27 48 201. Such valves are used as throttle valves, where it is important that the throttling positions can be accurately repeated, that is, the throttle positions have an accurately reproducible opening regardless of whether the throttle valve is moved into a given position from the closed or the opened position of the valve. This desired feature of the throttle valve is obtained with a higher degree of accuracy if the amount of play or tolerance between the moveable parts is maintained as low as possible. A significant feature in the design of such a throttle valve is that the valve movements must be easily reproducible with as few bearing and support parts as possible.
Easily reproducible movements are possible if the parts movable with respect to one another can be sealed reliably at a relatively small production cost.
If the previously known throttle valve is considered with the two embodiments disclosed in German patent document No. 27 48 201 in view of these requirements, then it must be noted that these requirements have not been adequately meet in either of the embodiments. The shutoff or cutoff part is pivotably and tiltably moveable, however, the movements of the cutoff part are achieved by a number of subdivided components and sliding guides. For each movement interruption and each guide condition, a corresponding bearing play is present and the sum of all these bearing clearances provide a situation which should be avoided, that is, wherein at least two different positions of the cutoff part correspond to one specific position of the actuating elements, which are operated externally, depending upon the direction from which the position is approached.